1. Field of the Invention
This invention generally relates to an external-device control apparatus, and also a system including an external device and a control apparatus for the external device. This invention particularly relates to an apparatus for extracting PSI (program specific information) from a transport stream generated in conformity with the MPEG2 (Moving Picture Experts Group 2) standards, and controlling an external device in response to the extracted PSI. In addition, this invention particularly relates to a system including such a control apparatus and an external device.
2. Description of the Related Art
A plurality of content programs (for example, television programs) can be transmitted on a multiplexed basis through the use of a transport stream (TS) generated in conformity with the MPEG2 standards. Program specific information (PSI) is contained in the transport stream. The PSI identifies what parts of the transport stream belong to a particular content program among the plural content programs. Specifically, the PSI includes information for identifying necessary packets (desired packets) from the transport stream in which the plural content programs are multiplexed. Accordingly, a reception side can select desired one from the plural content programs by extracting the PSI from the transport stream and then referring to the extracted PSI.
The PSI complies with the ISO/IEC13818-1 standards. In general, the PSI includes a program association table (PAT), a program map table (PMT), and a selection information table (SIT). There are various descriptors in these tables (for example, a PMT and a SIT) which are classified according to use.
Japanese patent application publication number 2004-104752 discloses a digital broadcast receiving apparatus including a storage unit, a first controller, a memory, a second controller, and an interface. The first controller and the second controller are formed by a common CPU. The first controller loads the storage unit with a partial TS (transport stream) extracted from a received TS. The partial TS includes elementary streams (ES) representative of a selected content program, and control information for the selected content program. The first controller generates program accessory information from the control information in the partial TS which occurs before being loaded into the storage unit. The program accessory information includes copy control information and packet identification information. The program accessory information is referred to when the partial TS is outputted to an external recording device from the storage unit. The memory stores the program accessory information in a manner having a correspondence with the partial TS in the storage unit. The second controller issues the interface a command to update the control information in the partial TS according to the program accessory information. Furthermore, the second controller issues the interface a command to read out the partial TS from the storage unit. When receiving the commands from the second controller, the interface reads out the partial TS from the storage unit and updates the control information according to the program accessory information. Then, the interface outputs the read-out partial TS to the external recording device.
In the apparatus of Japanese application 2004-104752, the control information in the partial TS extracted from the received TS includes a PMT having copy control information. The first controller extracts the copy control information from the PMT, and uses the extracted copy control information as a part of the program accessory information. In the case where the copy control information in the partial TS extracted from the received TS is in a “copy-once” state, the copy control information is changed to a “no-more-copies” state before the partial TS is stored into the storage unit. Therefore, in this case, the copy control information in the program accessory information in the memory is in the “copy-once” state while the copy control information in the partial TS in the storage unit is in the “no-more-copies” state. When the second controller receives user's request to move the partial TS from the storage unit, the second controller refers to the copy control information in the program accessory information. In the case where the copy control information in the program accessory information is in the “copy-once” state, the second controller commands the interface to read out the partial TS from the storage unit and to update the copy control information in the read-out partial TS from the “no-more-copies” to the “copy-once” state. In addition, the second controller commands the interface to update move-related information in the PMT in the partial TS from a “non-move” state to an “in-move” state. Furthermore, the second controller commands the interface to output the partial TS inclusive of the updated copy control information to the external recording device. When the second controller receives user's request to copy the partial TS in the storage unit, the second controller refers to the copy control information in the program accessory information. In the case where the copy control information in the program accessory information is in the “copy-once” state, the second controller commands the interface to inhibit the transmission of the partial TS from the storage unit to the external recording device.
In the apparatus of Japanese application 2004-104752, the copy control information is represented by a descriptor in the PMT which is contained in PSI (program specific information). There are various descriptors in the PSI such as a component descriptor indicating the type of a component signal and a content descriptor indicating the genre of a content program. It is desirable to more effectively use such descriptors.